Electrical conductor



Oct. 8, 1929. HADAMS 1,731,218

ELECTRI CAL CONDUCTOR Filed Oct. 5, 1922 Inventor Nathan HAdams,

by Hi5 Attorney tered by the .weakening and 60 tions may be varied Patented Oct. 8, 1929 UNITED STATES NATHAN H. ADAMS, OF SCHENECTADY, NEW YORK,

ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK ELECTRICAL CONDUCTOR Application filed October 5, 1922. Serial Ho. 592,597.

The present invention comprises an im: proved terminal for flexible conductors which consist of strands of fine wires. It is the ob ject of my invention to provide a strong,

'5 rugged terminal to which a good electrical connection may be made without locally overheating, or otherwise injuring the individual wires of the flexible strands.

Heretofore, difficulties have been encounembrittling of stranded or braided conductors by the use of fluxes when welding, soldering or brazing terminals to conductors. When such operations arecarried out in the open air copper 15 wires become oxidized and in the presence of reducing gas, copper becomes brittle. As stranded conductors are particularly intended to be used in app ratus such as circuit breakers in which conductors frequently are subjected to motion, brittleness may soon lead to a break hich may cause an expensive shutdown of large apparatus.

In accordance with my invention, I have provided a terminal conductor by causing the wires constituting a stranded conductor to be compacted or welded together by pressure to form a solid bar or plate with the aid of a small quantity of easily fusible metal having preferably a moderate alloying aflinityfor said wires. For example, in order to bind together under pressure fine copper wires to form a dense, solid metal, I employ a small quantity of lead-tin alloy in which lead preponderates and the tin is in amount suflicicnt only to cause the alloy to adhere to the surface of the copper.

The accompanying drawing illustrates, in Figs. 1 and 2, a stranded conductor assembled in a press with sheets of binder metal, and Fig. 3 shows in perspective the finished article.

The stranded ribbon-shaped conductors 4 of Fig. 1 consist of fine copper wires which, for example, ma be about 10 mils in diameter. Between t e strands are placed wafers 5 of an ea'sil fusible metal having a moderate alloying a nity for copper. For example, I have used with success an alloy of nine parts lead and one part tin, although those proporconsiderably. This alper, the alloy 5 is substantially the properties loy has a melting point of about 290 C. The wafers 5 may be about two mils in. thickness. An alloy of this constitution is not suitable for ordinary soldering but the high pressure and high temperature conditions of thepresent process renders the alloy capable of cansing the copper wires to be consolidated into a compact mass. The parts when assembled are placed between the members 6, 7 of a mold heatedunder a pressure suf'iciently high to melt the wafers 5 and to soften the copper. I may use for this purpose a press adapted to convey a heating current through the mass. In the drawing, I have indicated diagrammatically electric terminals 8, 9 by Which pressure may be applied. These terminals are connected to conductors 10, 11 preferably including between one of the mold members and the adjoining terminal a strip of material of relatively high resistance, for example a layer 12 consisting of A pressure of about two thousand pounds to the square inch ordinarily is satisfactory for the welding operation.

The temperature suitable for this compression and welding step ordinarily will lie within the limits of about 750 to 950 C., depending on the density desired in the terminal. Most commonly I use a temperature of about 850 C. At this temperature which approaches the softening temperature of cophighly fluid, so that to a large degree it escapes from the mass and is vaporized. Apparently the alloy acts as a flux to put the metal surfaces into proper condition for welding. Oxide on the surface of the copper wires is removed by the melted flux metal. Oxidized copper may be Welded as readily as clean, unoxidized copper.

The welded portion 13 of the conductor may be machined as shown in Fig. 3 to remove surface inequalities. The portion 13 presents to the unaided eye the appearance of a sound homogeneous metal and indeed, has of homogeneous copper. Under the microscope it can be observed to consist of a densely compacted mass in which the original wires or other components are still detectable, in most cases surrounded by a film of alloy.

graphite or carbon.

The compressed mass becomes more dense and homogeneous as the pressure and temperature of the operation are raised.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. An. article of manufacture comprising a plurality of members of metal united into a compact, unitary mass and a filmof binder metal located in interstices between said members, said binder metal having 1nsuflic1ent al loying aflinity for said members to materially attack the surface thereof but being capable of promoting welding of said members under pressure at a temperature approximating the melting point of said members '2. An electrical conductor comprising in part a multiplicity of flexible wires and in part a solid bar or plate, said plate comprising a continuation of said wires welded together and containing dispersed between said wires a film of alloy melting at about onethird the softening temperature of the wires.

3. An article of manufacture comprising i in part a plurality of filamentary copper wires and in part a substantially solid mass of metal constituted by said wires joined to each other by a film of alloy of lead and tin in which the tin is in amount sufficient to cause the alloy to adhere to the surface of the copper wires to promote a welding operation.

4. An article of manufacture comprising a, plurality of copper filaments and a solid, machinable bar continuous therewith and 5 having substantially the mechanical properties of a bar of copper of equal size, said bar comprising said filaments joined to each other by an intervening film of binder metal consisting largely of lead and in part of a metal alloyable with copper.

5. An article of manufacture comprising a bundle of filamentary wires consisting of copper compacted to form a solid mass, said wiresbeing in part welded to each other and in part joined to each other by a film of alloy which melts at a much lower temperature than the wires and which is present in such small proportionv that said mass has substantially the properties of homogeneous copper.

6. An article of manufacture comprising a multiplicityof separate members associated in a densely compacted state, said members being joined to one another by welding and by a film of alloy having a slight alloying atiinity for said members into a mass having the appearance to the unaided eye of sound, homogeneous metal and which when magnified can be seen to comprise distinct compo nent members. y

In witness whereof, I have hereunto set my hand this 4th day of October, 1922.

NATHAN H. ADAMS. 

